[Show abstract][Hide abstract] ABSTRACT: The Pulsed Electro Acoustic– PEA –method is used to perform space charge measurements in organic dielectrics subjected to electron beam irradiation as also during relaxation, under short-circuit and open-circuit conditions. A model based on GEANT 4 libraries for electron transport analysis has been developed in order to understand the behavior of space charge in space environment. Examples of measurements recorded on Polyimide films using various configurations are analyzed in the paper. A comparison between experimental data and simulated results shows that various complex phenomena are occurring simultaneously.
Journal of Electrostatics 05/2009; 67(2):400-406. DOI:10.1016/j.elstat.2009.01.003 · 0.86 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Different detection systems based on the pulsed electro acoustic (PEA) method have been developed in the last past few years to study space charge distribution in electron irradiated materials. In particular, a set-up working in contact less mode allowing the measurement to be done in open-circuit (where one surface of the irradiated sample is at a floating potential, so-called "open PEA") has been put forward recently. A reference signal is required in any case in order to get quantitative data. The calibration protocol adopted in the case of the classical PEA method, where the sample is under short-circuit condition, cannot be used any more in the "open" configuration. This paper deals with the description and validation of the procedure used to record a proper reference signal to treat raw data obtained with the "open PEA" set-up. Results recorded under various conditions will be compared.
[Show abstract][Hide abstract] ABSTRACT: The charge distribution in low density pyethylene and polyimide films under a quasi-mono-energetic electron beam irradiation in the range [5–400 keV] is analysed using a new experimental set-up based on the pulsed electro-acoustic (PEA) method. The device allows measurements without any physical contact between the excitation electrode used in the PEA method and the irradiated surface which remains at a floating potential during the entire duration of the experiment. This special configuration makes it possible to study bulk as well as interface phenomena. In particular, emission of charges from the irradiated surface to the vacuum is in evidence as well as charge injection from the ground electrode to the bulk. The time-dependent charge distribution during irradiation is approached by combining a Monte Carlo toolkit for modelling radiation transport in matter in conjunction with a macroscopic description of charge transport based on the concept of a radiation-induced conductivity generated by the injected electrons. Although the macroscopic description yields a fair agreement with the experimental data, it fails to depict the detailed shape of the charge distribution, thereby calling for a microscopic, bi-polar model.
Journal of Physics D Applied Physics 10/2008; 41(20):205417. DOI:10.1088/0022-3727/41/20/205417 · 2.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We introduce a pulsed electro acoustic (PEA) device enabling space charge measurement inside dielectric films without the need of sample to excitation unit contact. The new device -called open PEA because one face of the film is at a floating potential- has been used to investigate the internal charge of electron beam irradiated dielectrics. Details are given on the system and its calibration for performing quantitative charge measurements. Charge distributions in electron beam irradiated polytetrafluoroethylene (PTFE) films are compared using the classical and the open PEA. Due to the short-circuit condition in the classical PEA, the implanted charges measured using the two systems are drastically different. Surface potential and current measurements performed during irradiation have been used to validate the measurement in the open configuration which is well suited to investigate the behaviour of dielectrics in space environment.
IEEE Transactions on Dielectrics and Electrical Insulation 09/2008; 15(4-15):958 - 964. DOI:10.1109/TDEI.2008.4591216 · 1.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Kapton® and poly(tetrafluoroethylene) (PTFE) are insulating materials that are commonly used in a space environment, notably in applications for the thermal regulation of satellites. When the satellite is in a geostationary orbit these materials are subjected to a flux of charged particles trapped in the radiation belts, and particularly to energetic electrons. They can accumulate charges due to their dielectric properties, which generate localized increases of the electric field in the material bulk that can lead to an electrostatic discharge. This phenomenon could involve serious damage to the satellite structure or performance. A behavioral study of Kapton® and PTFE materials under electronic irradiation could be helpful to understand the charge transport in the body of the material and allow a discharge control strategy to be developed. In the present study, two different measurement tools have been combined — classical surface potential measurements and Pulse Electro-Acoustic (PEA) measurements — which give information on the charge distribution in the bulk. The latter method has been further adapted for use in a vacuum during the sample irradiation and measurements under various conditions have been performed. Two measurement configurations for the irradiated sample have been studied. In the first configuration, the irradiated sample surface is grounded during the whole irradiation period. In contrast, the second configuration is one in which the irradiated sample surface is left at floating potential. Measurements made with the PEA method in both the configurations will be compared in this article, in order to determine the main physical mechanisms of charge transport occurring during the bulk sample irradiation for each irradiation configuration.
High Performance Polymers 08/2008; 20(4-5):535-548. DOI:10.1177/0954008308089714 · 1.29 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Several types of polymeric materials are used in satellites wings and body. When these dielectrics are submitted to an electronic irradiation, sudden discharge might occur after a period of accumulation. To get a better knowledge on the charging and discharging phenomena in dielectrics, experimental studies are performed on earth. We focused our studies on the effect of the electronic irradiation, which is the main cause of charging, on polymeric films. Between two periods of irradiation and during the relaxation classic surface potential measurements are performed. The space charge distribution in the bulk is followed thanks to the pulse electro acoustic (PEA) method adapted to work under the appropriated configuration. We completed our studies by a series of simulations.
[Show abstract][Hide abstract] ABSTRACT: Charges accumulate on the spacecraft surface through various processes such as conduction, irradiation, ionization, and polarization. These charges can affect the space system operations via an electric current flowing in the structure or a locally generated electric field. This paper is focused on the analysis of electron behavior in polymeric films such as polymethylmetaacrylate and Teflon subjected to an electron irradiation. The charge distribution is detected during and after the irradiation in situ by pulsed electroacoustic method. Surface-potential and surface-current measurements are also performed to get further information on the charge displacement with time
[Show abstract][Hide abstract] ABSTRACT: Various types of polymeric films can be found in satellites and especially in the main body. Among them, the polyimide type Upilexreg is often selected as it is offering high temperature resistance. However, due to its nature it can get charged and store polarized particles on the surface or in bulk up to a critical level. During the irradiation the built up of charges is followed by the pulsed electro-acoustic (PEA) method. The aim of this work is to get a better understanding on charge storage, conduction processes and extraction means in dielectric films submitted to a controlled electron irradiation, to prevent catastrophic damage during flight.
[Show abstract][Hide abstract] ABSTRACT: Charges can appear on spacecraft surface via various processes including conduction, irradiation, ionisation and polarisation. The accumulation of charges can leads to the creation of an electric field that eventually prevents further charge storage. However, a spacecraft can only tolerate a limited range of electric potential and currents. In the present case, we are studying the electron behaviour in polymeric films such as Teflon® during electronic irradiation. This material is currently used in the space industry. Our aim is to get a better understanding on charge storage, conduction and relaxation during irradiation and also during the relaxation taking especially into account the effect of the electron beam energy, the irradiation time and the flux density. Results obtained from pulsed electro-acoustic, surface current and surface potential data are analysed and compared with theoretical data.
[Show abstract][Hide abstract] ABSTRACT: Spacecrafts such as most of commercial satellites that are operating in the geostationary orbit can be subjected to intense irradiation by charged particles. The surface made of dielectric materials can therefore become probable sites for damaging electrostatic discharges. Thanks to a specially equipped chamber, the spatial environment can be reproduced experimentally in the laboratory. In this paper, the behavior of high energy electrons injected in polymers such as PolyMethylMetaAcrylate (PMMA) and Kapton® is studied. Results obtained by surface potential technique, pulse-electro acoustic device and a cell based on the split Faraday cup system are analyzed and discussed.
Electrical Insulating Materials, 2005. (ISEIM 2005). Proceedings of 2005 International Symposium on; 07/2005